The present invention relates to a producing method of ball for ball game.
A soccer ball or volleyball is generally made up by a ball cover and a bladder disposed within the ball cover. The ball cover is made of leather, synthetic leather such as polyurethane (PU) or polyvinyl chloride (PVC) or laminated material. The synthetic leather is composed of an outer coating layer, an intermediate forming layer and an inner lining layer to strengthen and support the intermediate forming layer. The bladder is a spherical rubber ball having a valve stem attached thereon.
The leather or synthetic leather is cut into a plurality of panels with a predetermined shape. For a soccer ball, the most common shape of panel is pentagon and hexagon. In other words, the ball cover of a soccer ball is generally made of 12 pieces of pentagonal panels and 20 pieces of hexagonal panels by sewing edge to edge. The spherical ball cover of a volleyball is made of 18 pieces of rectangular panels by sewing to edge, for example. An inflatable bladder is disposed inside the ball cover and its valve stem is extended outside the ball cover for air inflation. When air is pumped into the bladder through the valve stem, the air inflates the bladder to prop up the ball cover and retain its roundness. Therefore, the more air is inflated into the bladder, the sportsball has a better bounce.
The invention with an object of providing a sportsball which supports the ball cover by a reinforced bladder is disclosed in U.S. Pat. No. 5,772,545.
The sportsball disclosed in U.S. Pat. No. 5,772,545 includes a ball cover and a bladder. The ball cover has a valve hole provided thereon and consists of a plurality of panels connected edge to edge by a sewing machine to form a roundness shape. Each of the panels has a predetermined shape and is made of synthetic leather. The synthetic leather has an outer coating layer, an inner lining layer, and an intermediate layer which is integrally formed between the outer coating layer and the inner lining layer and is strengthened and supported by the inner lining layer. The bladder disposed within the ball cover includes a bladder ball made of rubber, an exterior web layer integrally attached on a predetermined area of an outer surface of the bladder ball and a valve stem which is mounted on the bladder ball and is extended through the valve hole of the ball cover connected thereto for air inflation. The web layer includes at least an elongated strengthened thread evenly wound around the entire outer surface of the bladder ball. The strengthened thread is overlapped to form the web layer to entirely embrace the bladder ball for supporting the bladder ball and resisting the stress and impact force applied to the sportsball. The panels of the ball cover may also be made of thin leather with a pad layer adhered underneath for providing the softness and thickness of the ball cover.
The manufacturing method disclosed in U.S. Pat. No. 5,772,545 includes following steps:
(a) Inflate a rubber bladder ball having a valve stem provided thereon.
(b) Coat at least an elongated strengthened thread such as nylon threads with an adhesive agent (or glue)
(c) Wind the nylon thread evenly around an outer surface of the rubber bladder ball until the bladder ball is embraced by a web layer of the nylon thread to form a strengthened bladder.
(d) Heat the bladder in a mold until the web layer is permanently and rigidly united with the outer surface of the bladder ball.
(e) Cut a ball cover material (for example, leather or synthetic leather including a sponge material made of foaming polyurethane or polyvinyl chloride) into a predetermined number of panels in a predetermined shape (12 pieces of pentagonal panels and 20 pieces of hexagonal panels are cut for a soccer ball, and 18 pieces of panels in two kinds of rectangular shape are cut for a volleyball).
(f) Sew the panels edge to edge together by a sewing machine to form a ball cover which has a valve hole provided thereon (a section of the panels are not sewn together to form an inlet opening at this stage).
(g) Heat the ball cover and turn the ball cover right side out.
(h) Insert the strengthened bladder into the ball cover through the inlet opening.
(i) Align and apply adhesive agent (or glue) on the valve stem of the bladder with the valve hole of the ball cover.
(j) Semi-inflate the bladder to make sure that the inflated bladder would prop against the ball cover.
(k) Sew the inlet opening of the ball cover together by hand.
(l) Fully inflate the sportsball to more than a standard pressure within a shaping mold to ensure a permanent structure and shape of the bladder and ball cover.
According to the invention disclosed in U.S. Pat. No. 5,772,545, in order to solve the problem of providing a sportsball for supporting the ball cover with the strengthened bladder, step (d) “Heat the bladder in a mold until the web layer is permanently and rigidly united with the outer surface of the bladder ball” and step (g) “Heat the ball cover and turn the ball cover right side out” must be included. Accordingly, there has been a problem in safety (in other words, it is dangerous) besides the problems of complex manufacturing steps and requiring facility for heating adhesive agent.